[net-next-2.6.git] / net / ipv4 / netfilter / nf_nat_sip.c

/* SIP extension for UDP NAT alteration.
 *
 * (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
 * based on RR's ip_nat_ftp.c and other modules.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/udp.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_nat_rule.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sip.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
MODULE_DESCRIPTION("SIP NAT helper");
MODULE_ALIAS("ip_nat_sip");


static unsigned int mangle_packet(struct sk_buff *skb,
				  const char **dptr, unsigned int *datalen,
				  unsigned int matchoff, unsigned int matchlen,
				  const char *buffer, unsigned int buflen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

	if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
				      buffer, buflen))
		return 0;

	/* Reload data pointer and adjust datalen value */
	*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
	*datalen += buflen - matchlen;
	return 1;
}

static int map_addr(struct sk_buff *skb,
		    const char **dptr, unsigned int *datalen,
		    unsigned int matchoff, unsigned int matchlen,
		    union nf_inet_addr *addr, __be16 port)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	unsigned int buflen;
	__be32 newaddr;
	__be16 newport;

	if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip &&
	    ct->tuplehash[dir].tuple.src.u.udp.port == port) {
		newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
		newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
	} else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip &&
		   ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
		newaddr = ct->tuplehash[!dir].tuple.src.u3.ip;
		newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
	} else
		return 1;

	if (newaddr == addr->ip && newport == port)
		return 1;

	buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
			 NIPQUAD(newaddr), ntohs(newport));

	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static int map_sip_addr(struct sk_buff *skb,
			const char **dptr, unsigned int *datalen,
			enum sip_header_types type)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchlen, matchoff;
	union nf_inet_addr addr;
	__be16 port;

	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL,
				    &matchoff, &matchlen, &addr, &port) <= 0)
		return 1;
	return map_addr(skb, dptr, datalen, matchoff, matchlen, &addr, port);
}

static unsigned int ip_nat_sip(struct sk_buff *skb,
			       const char **dptr, unsigned int *datalen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	unsigned int matchoff, matchlen;
	union nf_inet_addr addr;
	__be16 port;
	int request;

	/* Basic rules: requests and responses. */
	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
		if (ct_sip_parse_request(ct, *dptr, *datalen,
					 &matchoff, &matchlen,
					 &addr, &port) > 0 &&
		    !map_addr(skb, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;
		request = 1;
	} else
		request = 0;

	/* Translate topmost Via header and parameters */
	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
				    SIP_HDR_VIA, NULL, &matchoff, &matchlen,
				    &addr, &port) > 0) {
		unsigned int matchend, poff, plen, buflen, n;
		char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];

		/* We're only interested in headers related to this
		 * connection */
		if (request) {
			if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip ||
			    port != ct->tuplehash[dir].tuple.src.u.udp.port)
				goto next;
		} else {
			if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip ||
			    port != ct->tuplehash[dir].tuple.dst.u.udp.port)
				goto next;
		}

		if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;

		matchend = matchoff + matchlen;

		/* The maddr= parameter (RFC 2361) specifies where to send
		 * the reply. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "maddr=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
			__be32 ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
			buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
			if (!mangle_packet(skb, dptr, datalen, poff, plen,
					   buffer, buflen))
				return NF_DROP;
		}

		/* The received= parameter (RFC 2361) contains the address
		 * from which the server received the request. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "received=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
			__be32 ip = ct->tuplehash[!dir].tuple.src.u3.ip;
			buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
			if (!mangle_packet(skb, dptr, datalen, poff, plen,
					   buffer, buflen))
				return NF_DROP;
		}

		/* The rport= parameter (RFC 3581) contains the port number
		 * from which the server received the request. */
		if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
						 "rport=", &poff, &plen,
						 &n) > 0 &&
		    htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
		    htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
			buflen = sprintf(buffer, "%u", ntohs(p));
			if (!mangle_packet(skb, dptr, datalen, poff, plen,
					   buffer, buflen))
				return NF_DROP;
		}
	}

next:
	if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM) ||
	    !map_sip_addr(skb, dptr, datalen, SIP_HDR_TO) ||
	    !map_sip_addr(skb, dptr, datalen, SIP_HDR_CONTACT))
		return NF_DROP;
	return NF_ACCEPT;
}

static int mangle_content_len(struct sk_buff *skb,
			      const char **dptr, unsigned int *datalen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchoff, matchlen;
	char buffer[sizeof("65536")];
	int buflen, c_len;

	/* Get actual SDP length */
	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
				  SDP_HDR_VERSION, SDP_HDR_UNSPEC,
				  &matchoff, &matchlen) <= 0)
		return 0;
	c_len = *datalen - matchoff + strlen("v=");

	/* Now, update SDP length */
	if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
			      &matchoff, &matchlen) <= 0)
		return 0;

	buflen = sprintf(buffer, "%u", c_len);
	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static unsigned mangle_sdp_packet(struct sk_buff *skb,
				  const char **dptr, unsigned int *datalen,
				  enum sdp_header_types type,
				  char *buffer, int buflen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	unsigned int matchlen, matchoff;

	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen, type, SDP_HDR_UNSPEC,
				  &matchoff, &matchlen) <= 0)
		return 0;
	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
			     buffer, buflen);
}

static unsigned int mangle_sdp(struct sk_buff *skb,
			       enum ip_conntrack_info ctinfo,
			       struct nf_conn *ct,
			       __be32 newip, u_int16_t port,
			       const char **dptr, unsigned int *datalen)
{
	char buffer[sizeof("nnn.nnn.nnn.nnn")];
	unsigned int bufflen;

	/* Mangle owner and contact info. */
	bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_OWNER_IP4,
			       buffer, bufflen))
		return 0;

	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_CONNECTION_IP4,
			       buffer, bufflen))
		return 0;

	/* Mangle media port. */
	bufflen = sprintf(buffer, "%u", port);
	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_MEDIA,
			       buffer, bufflen))
		return 0;

	return mangle_content_len(skb, dptr, datalen);
}

static void ip_nat_sdp_expect(struct nf_conn *ct,
			      struct nf_conntrack_expect *exp)
{
	struct nf_nat_range range;

	/* This must be a fresh one. */
	BUG_ON(ct->status & IPS_NAT_DONE_MASK);

	/* For DST manip, map port here to where it's expected. */
	range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
	range.min = range.max = exp->saved_proto;
	range.min_ip = range.max_ip = exp->saved_ip;
	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);

	/* Change src to where master sends to */
	range.flags = IP_NAT_RANGE_MAP_IPS;
	range.min_ip = range.max_ip
		= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
}

/* So, this packet has hit the connection tracking matching code.
   Mangle it, and change the expectation to match the new version. */
static unsigned int ip_nat_sdp(struct sk_buff *skb,
			       const char **dptr, unsigned int *datalen,
			       struct nf_conntrack_expect *exp)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	__be32 newip;
	u_int16_t port;

	/* Connection will come from reply */
	if (ct->tuplehash[dir].tuple.src.u3.ip ==
	    ct->tuplehash[!dir].tuple.dst.u3.ip)
		newip = exp->tuple.dst.u3.ip;
	else
		newip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	exp->saved_ip = exp->tuple.dst.u3.ip;
	exp->tuple.dst.u3.ip = newip;
	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	exp->dir = !dir;

	/* When you see the packet, we need to NAT it the same as the
	   this one. */
	exp->expectfn = ip_nat_sdp_expect;

	/* Try to get same port: if not, try to change it. */
	for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
		exp->tuple.dst.u.udp.port = htons(port);
		if (nf_ct_expect_related(exp) == 0)
			break;
	}

	if (port == 0)
		return NF_DROP;

	if (!mangle_sdp(skb, ctinfo, ct, newip, port, dptr, datalen)) {
		nf_ct_unexpect_related(exp);
		return NF_DROP;
	}
	return NF_ACCEPT;
}

static void __exit nf_nat_sip_fini(void)
{
	rcu_assign_pointer(nf_nat_sip_hook, NULL);
	rcu_assign_pointer(nf_nat_sdp_hook, NULL);
	synchronize_rcu();
}

static int __init nf_nat_sip_init(void)
{
	BUG_ON(nf_nat_sip_hook != NULL);
	BUG_ON(nf_nat_sdp_hook != NULL);
	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
	rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
	return 0;
}

module_init(nf_nat_sip_init);
module_exit(nf_nat_sip_fini);
Commit	Line	Data
9fafcd7b PM	1	/* SIP extension for UDP NAT alteration.
	2	*
	3	* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
	4	* based on RR's ip_nat_ftp.c and other modules.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/ip.h>
c9bdd4b5	14	#include <net/ip.h>
9fafcd7b PM	15	#include <linux/udp.h>
	16
	17	#include <net/netfilter/nf_nat.h>
	18	#include <net/netfilter/nf_nat_helper.h>
	19	#include <net/netfilter/nf_nat_rule.h>
	20	#include <net/netfilter/nf_conntrack_helper.h>
	21	#include <net/netfilter/nf_conntrack_expect.h>
	22	#include <linux/netfilter/nf_conntrack_sip.h>
	23
	24	MODULE_LICENSE("GPL");
	25	MODULE_AUTHOR("Christian Hentschel <chentschel@arnet.com.ar>");
	26	MODULE_DESCRIPTION("SIP NAT helper");
	27	MODULE_ALIAS("ip_nat_sip");
	28
9fafcd7b	29
2a6cfb22 PM	30	static unsigned int mangle_packet(struct sk_buff *skb,
	31	const char *dptr, unsigned int datalen,
	32	unsigned int matchoff, unsigned int matchlen,
	33	const char *buffer, unsigned int buflen)
	34	{
	35	enum ip_conntrack_info ctinfo;
	36	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	37
	38	if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
	39	buffer, buflen))
	40	return 0;
	41
	42	/* Reload data pointer and adjust datalen value */
	43	*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
	44	*datalen += buflen - matchlen;
	45	return 1;
	46	}
	47
ac367740 PM	48	static int map_addr(struct sk_buff *skb,
	49	const char *dptr, unsigned int datalen,
	50	unsigned int matchoff, unsigned int matchlen,
624f8b7b	51	union nf_inet_addr *addr, __be16 port)
9fafcd7b	52	{
212440a7	53	enum ip_conntrack_info ctinfo;
624f8b7b	54	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
9fafcd7b	55	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
624f8b7b PM	56	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	57	unsigned int buflen;
	58	__be32 newaddr;
	59	__be16 newport;
	60
	61	if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip &&
	62	ct->tuplehash[dir].tuple.src.u.udp.port == port) {
	63	newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
	64	newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
	65	} else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip &&
	66	ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
	67	newaddr = ct->tuplehash[!dir].tuple.src.u3.ip;
	68	newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
9fafcd7b PM	69	} else
	70	return 1;
	71
624f8b7b PM	72	if (newaddr == addr->ip && newport == port)
	73	return 1;
	74
	75	buflen = sprintf(buffer, "%u.%u.%u.%u:%u",
	76	NIPQUAD(newaddr), ntohs(newport));
	77
2a6cfb22	78	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
624f8b7b	79	buffer, buflen);
9fafcd7b PM	80	}
9fafcd7b PM	81
ac367740 PM	82	static int map_sip_addr(struct sk_buff *skb,
ac367740 PM	83	const char *dptr, unsigned int datalen,
624f8b7b	84	enum sip_header_types type)
ac367740 PM	85	{
	86	enum ip_conntrack_info ctinfo;
	87	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	88	unsigned int matchlen, matchoff;
624f8b7b PM	89	union nf_inet_addr addr;
624f8b7b PM	90	__be16 port;
ac367740	91
624f8b7b PM	92	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen, type, NULL,
624f8b7b PM	93	&matchoff, &matchlen, &addr, &port) <= 0)
ac367740	94	return 1;
624f8b7b	95	return map_addr(skb, dptr, datalen, matchoff, matchlen, &addr, port);
ac367740 PM	96	}
ac367740 PM	97
3db05fea	98	static unsigned int ip_nat_sip(struct sk_buff *skb,
2a6cfb22	99	const char *dptr, unsigned int datalen)
9fafcd7b	100	{
212440a7 PM	101	enum ip_conntrack_info ctinfo;
212440a7 PM	102	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
720ac708	103	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
ac367740	104	unsigned int matchoff, matchlen;
624f8b7b PM	105	union nf_inet_addr addr;
624f8b7b PM	106	__be16 port;
720ac708	107	int request;
9fafcd7b	108
9fafcd7b	109	/* Basic rules: requests and responses. */
779382eb	110	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
ac367740	111	if (ct_sip_parse_request(ct, dptr, datalen,
624f8b7b PM	112	&matchoff, &matchlen,
	113	&addr, &port) > 0 &&
	114	!map_addr(skb, dptr, datalen, matchoff, matchlen,
	115	&addr, port))
9fafcd7b	116	return NF_DROP;
720ac708 PM	117	request = 1;
	118	} else
	119	request = 0;
	120
	121	/* Translate topmost Via header and parameters */
	122	if (ct_sip_parse_header_uri(ct, dptr, NULL, datalen,
	123	SIP_HDR_VIA, NULL, &matchoff, &matchlen,
	124	&addr, &port) > 0) {
	125	unsigned int matchend, poff, plen, buflen, n;
	126	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	127
	128	/* We're only interested in headers related to this
	129	* connection */
	130	if (request) {
	131	if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip \|\|
	132	port != ct->tuplehash[dir].tuple.src.u.udp.port)
	133	goto next;
	134	} else {
	135	if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip \|\|
	136	port != ct->tuplehash[dir].tuple.dst.u.udp.port)
	137	goto next;
	138	}
	139
	140	if (!map_addr(skb, dptr, datalen, matchoff, matchlen,
	141	&addr, port))
	142	return NF_DROP;
	143
	144	matchend = matchoff + matchlen;
	145
	146	/* The maddr= parameter (RFC 2361) specifies where to send
	147	* the reply. */
	148	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	149	"maddr=", &poff, &plen,
	150	&addr) > 0 &&
	151	addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
	152	addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
	153	__be32 ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
	154	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
	155	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	156	buffer, buflen))
	157	return NF_DROP;
	158	}
	159
	160	/* The received= parameter (RFC 2361) contains the address
	161	* from which the server received the request. */
	162	if (ct_sip_parse_address_param(ct, dptr, matchend, datalen,
	163	"received=", &poff, &plen,
	164	&addr) > 0 &&
	165	addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
	166	addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
	167	__be32 ip = ct->tuplehash[!dir].tuple.src.u3.ip;
	168	buflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(ip));
	169	if (!mangle_packet(skb, dptr, datalen, poff, plen,
	170	buffer, buflen))
	171	return NF_DROP;
	172	}
	173
	174	/* The rport= parameter (RFC 3581) contains the port number
	175	* from which the server received the request. */
	176	if (ct_sip_parse_numerical_param(ct, dptr, matchend, datalen,
	177	"rport=", &poff, &plen,
	178	&n) > 0 &&
	179	htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
	180	htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
181	__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
182	buflen = sprintf(buffer, "%u", ntohs(p));
183	if (!mangle_packet(skb, dptr, datalen, poff, plen,
184	buffer, buflen))
185	return NF_DROP;
186	}
9fafcd7b PM	187	}
9fafcd7b PM	188
720ac708	189	next:
624f8b7b PM	190	if (!map_sip_addr(skb, dptr, datalen, SIP_HDR_FROM) \|\|
624f8b7b PM	191	!map_sip_addr(skb, dptr, datalen, SIP_HDR_TO) \|\|
624f8b7b	192	!map_sip_addr(skb, dptr, datalen, SIP_HDR_CONTACT))
9fafcd7b PM	193	return NF_DROP;
	194	return NF_ACCEPT;
	195	}
	196
3e9b4600 PM	197	static int mangle_content_len(struct sk_buff *skb,
3e9b4600 PM	198	const char *dptr, unsigned int datalen)
9fafcd7b	199	{
212440a7 PM	200	enum ip_conntrack_info ctinfo;
212440a7 PM	201	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600 PM	202	unsigned int matchoff, matchlen;
	203	char buffer[sizeof("65536")];
	204	int buflen, c_len;
9fafcd7b	205
3e9b4600 PM	206	/* Get actual SDP length */
	207	if (ct_sip_get_sdp_header(ct, dptr, 0, datalen,
	208	SDP_HDR_VERSION, SDP_HDR_UNSPEC,
	209	&matchoff, &matchlen) <= 0)
	210	return 0;
	211	c_len = *datalen - matchoff + strlen("v=");
	212
	213	/* Now, update SDP length */
ea45f12a PM	214	if (ct_sip_get_header(ct, dptr, 0, datalen, SIP_HDR_CONTENT_LENGTH,
ea45f12a PM	215	&matchoff, &matchlen) <= 0)
9fafcd7b PM	216	return 0;
9fafcd7b PM	217
3e9b4600	218	buflen = sprintf(buffer, "%u", c_len);
2a6cfb22	219	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
3e9b4600	220	buffer, buflen);
9fafcd7b PM	221	}
9fafcd7b PM	222
3e9b4600 PM	223	static unsigned mangle_sdp_packet(struct sk_buff *skb,
	224	const char *dptr, unsigned int datalen,
	225	enum sdp_header_types type,
	226	char *buffer, int buflen)
9fafcd7b	227	{
212440a7 PM	228	enum ip_conntrack_info ctinfo;
212440a7 PM	229	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
3e9b4600	230	unsigned int matchlen, matchoff;
9fafcd7b	231
3e9b4600 PM	232	if (ct_sip_get_sdp_header(ct, dptr, 0, datalen, type, SDP_HDR_UNSPEC,
	233	&matchoff, &matchlen) <= 0)
	234	return 0;
	235	return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
	236	buffer, buflen);
9fafcd7b PM	237	}
9fafcd7b PM	238
3db05fea	239	static unsigned int mangle_sdp(struct sk_buff *skb,
9fafcd7b PM	240	enum ip_conntrack_info ctinfo,
	241	struct nf_conn *ct,
	242	__be32 newip, u_int16_t port,
2a6cfb22	243	const char *dptr, unsigned int datalen)
9fafcd7b PM	244	{
9fafcd7b PM	245	char buffer[sizeof("nnn.nnn.nnn.nnn")];
2a6cfb22	246	unsigned int bufflen;
9fafcd7b PM	247
	248	/* Mangle owner and contact info. */
	249	bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
3e9b4600 PM	250	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_OWNER_IP4,
3e9b4600 PM	251	buffer, bufflen))
9fafcd7b PM	252	return 0;
9fafcd7b PM	253
3e9b4600 PM	254	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_CONNECTION_IP4,
3e9b4600 PM	255	buffer, bufflen))
9fafcd7b PM	256	return 0;
	257
	258	/* Mangle media port. */
	259	bufflen = sprintf(buffer, "%u", port);
3e9b4600 PM	260	if (!mangle_sdp_packet(skb, dptr, datalen, SDP_HDR_MEDIA,
3e9b4600 PM	261	buffer, bufflen))
9fafcd7b PM	262	return 0;
9fafcd7b PM	263
212440a7	264	return mangle_content_len(skb, dptr, datalen);
9fafcd7b PM	265	}
9fafcd7b PM	266
cfd6c380 HX	267	static void ip_nat_sdp_expect(struct nf_conn *ct,
	268	struct nf_conntrack_expect *exp)
	269	{
	270	struct nf_nat_range range;
	271
	272	/* This must be a fresh one. */
	273	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
	274
cfd6c380 HX	275	/* For DST manip, map port here to where it's expected. */
	276	range.flags = (IP_NAT_RANGE_MAP_IPS \| IP_NAT_RANGE_PROTO_SPECIFIED);
	277	range.min = range.max = exp->saved_proto;
	278	range.min_ip = range.max_ip = exp->saved_ip;
cc01dcbd	279	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_DST);
3d244121 PM	280
	281	/* Change src to where master sends to */
	282	range.flags = IP_NAT_RANGE_MAP_IPS;
	283	range.min_ip = range.max_ip
	284	= ct->master->tuplehash[!exp->dir].tuple.dst.u3.ip;
	285	nf_nat_setup_info(ct, &range, IP_NAT_MANIP_SRC);
cfd6c380 HX	286	}
cfd6c380 HX	287
9fafcd7b PM	288	/* So, this packet has hit the connection tracking matching code.
9fafcd7b PM	289	Mangle it, and change the expectation to match the new version. */
3db05fea	290	static unsigned int ip_nat_sdp(struct sk_buff *skb,
212440a7 PM	291	const char *dptr, unsigned int datalen,
212440a7 PM	292	struct nf_conntrack_expect *exp)
9fafcd7b	293	{
212440a7 PM	294	enum ip_conntrack_info ctinfo;
212440a7 PM	295	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
9fafcd7b PM	296	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	297	__be32 newip;
	298	u_int16_t port;
	299
9fafcd7b	300	/* Connection will come from reply */
f4a607bf JB	301	if (ct->tuplehash[dir].tuple.src.u3.ip ==
	302	ct->tuplehash[!dir].tuple.dst.u3.ip)
	303	newip = exp->tuple.dst.u3.ip;
	304	else
	305	newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
9fafcd7b	306
cfd6c380	307	exp->saved_ip = exp->tuple.dst.u3.ip;
9fafcd7b PM	308	exp->tuple.dst.u3.ip = newip;
	309	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	310	exp->dir = !dir;
	311
	312	/* When you see the packet, we need to NAT it the same as the
	313	this one. */
cfd6c380	314	exp->expectfn = ip_nat_sdp_expect;
9fafcd7b PM	315
	316	/* Try to get same port: if not, try to change it. */
	317	for (port = ntohs(exp->saved_proto.udp.port); port != 0; port++) {
	318	exp->tuple.dst.u.udp.port = htons(port);
6823645d	319	if (nf_ct_expect_related(exp) == 0)
9fafcd7b PM	320	break;
	321	}
	322
	323	if (port == 0)
	324	return NF_DROP;
	325
2a6cfb22	326	if (!mangle_sdp(skb, ctinfo, ct, newip, port, dptr, datalen)) {
6823645d	327	nf_ct_unexpect_related(exp);
9fafcd7b PM	328	return NF_DROP;
	329	}
	330	return NF_ACCEPT;
	331	}
	332
	333	static void __exit nf_nat_sip_fini(void)
	334	{
	335	rcu_assign_pointer(nf_nat_sip_hook, NULL);
	336	rcu_assign_pointer(nf_nat_sdp_hook, NULL);
	337	synchronize_rcu();
	338	}
	339
	340	static int __init nf_nat_sip_init(void)
	341	{
d1332e0a PM	342	BUG_ON(nf_nat_sip_hook != NULL);
d1332e0a PM	343	BUG_ON(nf_nat_sdp_hook != NULL);
9fafcd7b PM	344	rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
	345	rcu_assign_pointer(nf_nat_sdp_hook, ip_nat_sdp);
	346	return 0;
	347	}
	348
	349	module_init(nf_nat_sip_init);
	350	module_exit(nf_nat_sip_fini);